The present invention is directed to a chuck for a drilling tool such as a drill bit and includes a chuck member with a central bore into which an anvil extend for transmitting percussive force to the drilling tool shank. At least two clamping jaws are located in the chuck member and are adjustably displaceable in guide channels extending through the chuck member.
A chuck for a driving tool is disclosed in DE-OS No. 34 16 966 with a tool bit clamped in a chuck member so that selectively rotational motion or rotational motion and percussive force can be imparted to the tool bit. The tool bit extends in this known chuck into a central bore of an essentially sleeve-shaped chuck member with an essentially cylindrically shaped shank positioned in the central bore. Several clamping jaws are arranged equi-angularly around the shank and hold the shank in a frictional engagement for transmitting rotational movement to the tool bit. In addition, for imparting rotational movement, the chuck includes a locking member radially displaceable in the central bore for a positive locking action into axially extending entrainment grooves located in the shank. The entrainment grooves have a length in excess of the length of the locking member to assure axial mobility of the tool bit in the chuck during the transmittal of rotational motion. Such axial mobility affords the simultaneous transmission of percussive force by an anvil extending into the central bore so that the percussive force is transmitted through the tool bit to the material being worked. If the tool bit is held by the clamping jaws with only a frictional lock, such as is the case if the shank does not have entrainment grooves, then blows directed by the anvil against the shank can cause the frictional lock to loosen. In such an arrangement, it is not possible to impart rotational motion exclusively and reliably to the tool bit by a frictional locking action of the clamping jaws.